Method for forming a body of concrete or similar material in the soil

ABSTRACT

A method of forming a body of concrete or similar material in the soil comprises the steps of making a hole in the soil, lowering into said hole a bag having a shape corresponding to that of the body to be formed and made of a flexible material which is water-permeable but substantially blocks the passage of the solid particles of the (concrete) mortar and filling said bag with the (concrete) mortar, whereby the bag is subjected to vibrations either during and/or directly after the filling.

iinited States Patent [1 1 Van Weele Apr. 23, 1974 METHOD FOR FORMING ABODY OF CONCRETE OR SIMILAR MATERIAL IN THE SOIL lnventor: AbrahamFrancois Van Weele,

Brugweg 78, Waddinxveen, Netherlands Filed: June 23,1972

Appl. No.2 265,487

ForeignApplication Priority Data June 25, 1971 Netherlands 7108860 us.Cl 1/5352, 61/53.6, 61/5164,

, 6l/53.7 Int. vCl E0211 5/38, E02d 5/60 Field of Search. 6l/53.64,53.52, 53.6,

References Cited UNITED STATES PATENTS 2/1970 Lamberton 61-/53.52

3,611,735 10/1971 Daczko ..61/53.64

Primary ExaminerJac'ob Shapiro Attorney, Agent, or Firm--McGlew andTuttle [57] ABSTRACT A method of forming a body of concrete or similarmaterial in the soil comprises the steps of making a hole in the soil,lowering into said hole a bag having a shape corresponding to that ofthe body to be formed and made of a flexible material which iswaterpermeable but substantially blocks the passage of the solidparticles of the (concrete) mortar and filling said bag with the(concrete) mortar, whereby the bag is subjected to vibrations eitherduring and/or directly after the filling.

6 Claims, 3 Drawing Figures PATENTEDAPR 23 I974 FIG.2

FIG.1

1 METHOD FOR FORMING A BODY OF CONCRETE OR SIMILAR MATERIAL IN THE SOILSUMMARY OF THE INVENTION BACKGROUND AND PRIOR ART The use of bags whenforming concrete bodies, usually piles, in the soil is well known in theart. A main reason for the use of a bag is to obtain a casing and/or tokeep the (concrete)-mortar from direct contact with the surrounding soilparticles or with the underground water, respectively, in order to avoidthe detrimental influences of soil particles, or of the undergroundwater, respectively, on the quality of the ultimate body.

The art according to U.S. Pat. No. 3,396,545 recognizes that, that witha suitable selection of the material of the bag and particularly with asuitable choice of the mesh size of e.g., a polyamide fabric, the bagmay function as a filter which tends to retain the solid particles ofthe still flowing (concrete) mortar but permits the passage of the watertherein. The advantage of such a filtering effect is to be seen in thatthe water-cement factor is substantially reduced before the mortarbegins to set up. Due to this, the quality of the ultimate body isimproved. On the other hand, however, a relatively high water-cementfactor facilitates the transportation and the casting of the (concrete)mortar. According to the teaching of the above mentioned U.S. patent,the mortar may thus be handled and put into place with a relatively highwater-cement factor, while the setting process may still take place witha low water-cement factor. I

A complicating factor, however, is to be seen in that according to theprior art teaching, the mortar has to be introduced under arelativelyhigh pressure and has to be keptunder saidpressure thereafter duringsome time in order to have the filtering action take place withcertainty prior to the start of the setting process. With DESCRIPTION OFTHE INVENTION Now according to the present invention, the abovedescribed filtering action may be promoted or made less dependent on thepressure applied to the mortar respectively by subjecting the castingbag to vibrations either during and/or directly after filling. Due tothe vibrations, the contents of the bag reach a more fluidizedcondition. As a consequence the water in the mortar becomes less firmlybonded to the solid particles and is permitted to flow off towards thesurrounding soil. The filtering bed of the solid particles of the mortarwhich, according to the theory of the said prior art U.S. patent is,formed interiorly of the bag wall will, due to the vibration, be broughtin a less static condition. By this means the water is readily releasedand permitted to pass without the filter bed particles themselvespassing through the bag wall. Moreover, this effect is uniform throughthe full depth of the casting bag so that the vertical dimensions of thebody to be formed do no longer constitute a limiting factor as with thewell-known method used up till now. Experiments have been made, wherebypile bodies formed in accordance with the teachings of the presentinvention, showed a substantially constant improvement of mechanicalstrength. This could not be explained only by the improved packing ofthe material due to the vibration. Therefore, this clearly indicated auniform filtering effect along the complete length of the casting bag.

For effecting the vibrations a number of needle shaped vibration meansmay be driven in closely along the exterior of the filled bag and/orinto the bag.

A practical and economical, and therefore, preferred method, isparticularly suited for the forming of pile shaped bodies. According tothis method, tubular vibration means surrounding the casting bag isapplied, and by means of this first the hole in the soil is made andthen this means is extracted from the soil after the filling of the bagwhile the bag .is being subjected to vibrations. I

By this method the discharge of the water, which is released during thevibration of the material in the bag, may occur in the most favourablemanner, for the discharge of the water then starts from the lower end ofthe bag and extends gradually upwardly as the 'water is permitted toescape via the gradually upwardly moving lower edge of the tubularvibration means. Thus, the

upper (concrete) mortar, which has not yet been drained and is stillin areadily flowing state, may continue flowing downwardly to occupy thespace freed by the setting of the underlying mortar mass.

it is to be noted that it has been known before to form a concrete pilein the soil, whereby the concrete mortar is cast into a hole made in thesoil by means of a tube which is finally extracted from the soil whilebeing subjected to vibrations. In that case, however, no bag surroundingthe mortar is applied and therefore no filtering action reducing thewater-cement factor is obtained. According to the latter well-knownmethod an enlarged foot may be formed on the pile by lifting the tube inthe first part of its lifting movement with a relatively low velocity.

With the method according to the invention such an enlarged foot, whichfavourably influences the load bearing capacity of the pile, may berealized as well, namely by applying a bag which is open at its lowerend and which is inserted with its lower end up to a distance from thelower edge of the tube. However, smaller differences in cross-sectionaldimensions may also be obtained by differences in lifting velocity inthe pile portions which are surrounded by the resilient bag.

The invention also relates to a (concrete) body formed in the soil andobtainedby the application of the method according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic verticalsection through a tube having a lost shoe which has just been driveninto the soil together with the casting bag with the application of aspecial vibration assembly, in order to form a pile shaped concretebody;

FIG. 2 illustrates the next phase of the method according to theinvention in which the casting bag has been filled with mortar and thevibrating tube has already been extracted through a certain distancefrom the soil, while the shoe is left in place and FIG. 3 shows thesituation after the tube has been fully extracted and illustrates thefinished pile body.

DESCRIPTION OF SPECIFIC EMBODIMENTS The invention will be betterunderstood with reference to the illustrative drawings described herein.

A substantially cylindrical tube 1 of a type known per se is provided atits lower end with a so-called lost shoe la and has been driven into thesoil by means of a special vibration assembly 2. Said vibration assemblyhas a central portion 3 which may be clamped around the tube 1 at everydesired position by supplying a pressure fluid. The assembly 2 is thenlowered by a crane or similar device not further shown. Prior to drivingthe tube 1 into the soil first the casting bag 4, which is open at itslower end and consists of a fabric of polyamide or polyester, has beeninserted into the tube 1. The bag 4 is provided at its lower end with. astiffening ring 5 and is secured via said ring to the shoe la by meansof a number of binding wires 6. The bag 4 is secured at its upper end toa tube section 7 which has been inserted into the upper end of the tube1 and may be provided with means for suspending a reinforcementstructure for the pile body to be formed. The bag is kept drawn tautprior to and during the filling by the tensioning lines indicated 8which are in engagement with the tube section 7. The bag 4 has its loweredge prior to the filling step at a certain distance, e.g., 1 meter,above the shoe la.

In the situation according to FIG. 1 the bag 4 is about to be filledwith (concrete) mortar through the tube section 7 and the schematicallyindicated filling tube 9.

FIG. 2 shows the situation after the casting bag 4 having been filledand the tube 1 has already been lifted through a certain distance x(e.g., 1 meter) while being subjected to vibrations at a frequency inthe order of 500 to 1,000 longitudinal vibrations per minute. Thevelocity with which said first part of the total lifting movement hasbeen covered is kept relatively low, e.g., in the order of 1 meter perminute. With said moderate lifting velocity the portion of the fillingwhich has been released with the upward movement of the tube has metwith a moderate resistance in the surrounding zone of the soil to itstendency to drive out laterally, because of said surrounding zone of thesoil remaining strongly under the influence of the vibrations of thelifting tube at said low lifting velocity and therefore remaining in arelatively highly fluidized condition and thereby offering lessresistance. In this manner, as appears from the drawing, the lowerportion of the mortar filling has expanded to a relatively wide pilefoot. In this connection it is remarked that, as hasbeen found byexperiments, the pouring bag has stretched in the depth direction duringthe filling so that the lower edge of the bag after filling has arrivedat a shorter distance above the shoe la.

FIG. 3 shows the final stage of the method according to the inventionwhich is obtained when, starting from the situation according to FIG. 2,the tube is lifted through the remaining lifting height y at a highervelocity, e.g., in the order of 5 to 10 meters per minute. With saidhigher lifting velocity the bag filling has been able to expandsubstantially less, so that the obtained pile body has an enlarged footwhich considerably increases the load bearing capacity of the pile.

It has to be remarked in this respect that from the start of the liftingmovement of the vibrating tube 1 the water which is undesirable inconnection with the low water-cement factor in view, is released alongthe complete length of the filled bag from its adherence to the solidmortar particles. However, the discharge of water takes place gradually,via the lower edge of the tube 1 gradually moving upwardly. In eachphase of the lifting movement of the tube, the water in the portion ofthe bag filling which is still surrounded by the tube and already hasbeen released for the discharge, but has not yet been really discharged,keeps said portion of the bag filling in a condition in which it mayeasily flow and thereby fill the volume released by the expansion of theunderlying bag filling. The discharge of the water released by thevibration thereby is postponed to the moment in which the mortar is nolonger wanted to flow down.

It is finaly remarked that the filling of the bag and the vibration ofit must not be necessarily awaited until the hole has been formed. Itmight even be preferred to fill the bag as it is lowered with the tubeinto the soil. This procedure provides a better control of the fillingstep.

I claim:

1. Method of forming a body of concrete or similar material in the soilcomprising: making a hole in the soil; lowering into the hole a baghaving a shape corresponding to that of the body to be formed and madeof a flexible material which is water-permeable but substantially blocksthe passage of the solid particles of the (concrete) mortar; filling thebag with the (concrete) mortar; and subjecting the bag to vibrationsacting on its radially outer peripheral surface to compact the fillingby flow of excess water of the filling radially outwardly through theside wall of the bag.

2. The method according to claim 1, comprising subjecting the bag tosuch vibrations initially over its entire length; then progressivelyreducing, upwardly of the bag, the length thereof subjected to suchvibrations.

3. The method according to claim 2, comprising lowering, into the hole,a tube surrounding the bag; and subjecting the tube to such vibrationswhile extracting the tube out of the soil leaving the bag in the hole.

4. Method of forming a body of concrete or similar material in the soilcomprising: making a hole in the soil; lowering into said hole a baghaving a shape corresponding to that of the body to be formed and madeof a flexible material which is water-permeable but substantially blocksthe passage of the solid particles of the (concrete) mortar and fillingsaid bag with the (concrete) mortar; subjecting the bag to vibrationseither during and/or directly after filling; applying tubular vibratingmeans surrounding the bag, first making the hole in the soil extractingsaid means from the soil while subjecting said means to vibrations afterthe filling of the bag; and keeping the bag tautly tensioned prior toand during the filling by anchoring the bag at its lower end andsecuring the upper end of the bag to a tensioning element inserted inthe upper end of the tube.

5. The method according to claim 4, which comprises lowering the baginto the tube so far that said bag exsponding to that of the body to beformed and made of a flexible material which is water-permeable butsubstantially blocks the passage of the solid particles of the(concrete) mortar and filling said bag with the (concrete) mortar;subjecting the bag to vibrations either during and/or directly afterfilling; applying tubular vibrating means surrounding the bag, firstmaking the hole in the soil; extracting said means from the soil whilesubjecting said means to vibrations after the tilling of the bag;lowering the bag into the tube so far that said bag extends with itslower edge to a distance above the lower end of the tube, which is stillcompletely inserted in the soil, which distance substantiallycorresponds to the height of an enlarged pile foot; lifting the tube inthe first part of its lifting movement with a lower velocity than in theremaining part of the lifting movement; and forming said enlarged pilefoot.

1. Method of forming a body of concrete or similar material in the soilcomprising: making a hole in the soil; lowering into the hole a baghaving a shape corresponding to that of the body to be formed and madeof a flexible material which is water-permeable but substantially blocksthe passage of the solid particles of the (concrete) mortar; filling thebag with the (concrete) mortar; and subjecting the bag to vibrationsacting on its radially outer peripheral surface to compact the fillingby flow of excess water of the filling radially outwardly through theside wall of the bag.
 2. The method according to claim 1, comprisingsubjecting the bag to such vibrations initially over its entire length;then progressively reducing, upwardly of the bag, the length thereofsubjected to such vibrations.
 3. The method according to claim 2,comprising lowering, into the hole, a tube surrounding the bag; andsubjecting the tube to such vibrations while extracting the tube out ofthe soil leaving the bag in the hole.
 4. Method of forming a body ofconcrete or similar material in the soil comprising: making a hole inthe soil; lowering into said hole a bag having a shape corresponding tothat of the body to be formed and made of a flexible material which iswater-permeable but substantially blocks the passage of the solidparticles of the (concrete) mortar and filling said bag with the(concrete) mortar; subjecting the bag to vibrations either during and/ordirectly after filling; applying tubular vibrating means surrounding thebag, first making the hole in the soil extracting said means from thesoil while subjecting said means to vibrations after the filling of thebag; and keeping the bag tautly tensioned prior to and during thefilling by anchoring the bag at its lower end and securing the upper endof the bag to a tensioning element inserted in the upper end of thetube.
 5. The method according to claim 4, which comprises lowering thebag into the tube so far that said bag extends with its lower edge to adistance above the lower end of the tube, which is still completelyinserted in the soil, which distance substantially corresponds to theheight of an enlarged pile foot, lifting the tube in the first part ofits lifting movement with a lower velocity than in the remaining part ofthe lifting movement, and forming said enlarged pile foot.
 6. Method offorming a body of concrete or similar material in the soil comprising:making a hole in the soil; lowering into said hole a bag having a shapecorresponding to that of the body to be formed and made of a flexiblematerial which is water-permeable but substantially blocks the passageof the solid particles of the (concrete) mortar and filling said bagwith the (concrete) mortar; subjecting the bag to vibrations eitherduring and/or directly after filling; applying tubular vibrating meanssurrounding the bag, first making the hole in the soil; extracting saidmeans from the soil while subjecting said means to vibrations after thefilling of the bag; lowering the bag into the tube so far that said bagextends with its lower edge to a distance above the lower end of thetube, which is still completely inserted in the soil, which distancesubstantially corresponds to the height of an enlarged pile fooT;lifting the tube in the first part of its lifting movement with a lowervelocity than in the remaining part of the lifting movement; and formingsaid enlarged pile foot.